Various methods have been applied to reduce noise in air ducts of a passenger vehicle. One approach attempts to improve the grill on an instrument panel of the vehicle, as described in U.S. Pat. No. 4,957,036.
The inventors herein have recognized a disadvantage with prior art noise reduction systems for climate control systems of passenger vehicles. Specifically, such system can have duct systems with significant amounts of bending, or other discontinuities, so that the system can be packaged into the vehicle. This is especially true with more modern vehicle designs where space outside the passenger compartment is at a premium. Air flowing around these bends, or through other discontinuities, can produce noise due to turbulent air flow caused by a blower fan. In one example, this can noise can be due to impingement from turbulence on the discontinuities. This noise can be bothersome to customers, especially during high fan speed operation, or when the fan is first turning on.
Note that various types of discontinuities can be encountered, such as (i) a bend in a duct, (ii) an irregular flow path surface at a coupling between two ducts, (iii) a change in the diameter of a duct, (iv) an air filter, or (v) any other flow restriction in the exhaust pipe portion.
To overcome these disadvantages, a set of radial vanes can be used in the climate control system ducts upstream of the bends or discontinuities. In this way, it is possible to reduce the turbulence of the flow around the bends or discontinuities, thereby reducing the noise.
An advantage of the radial vanes is that they can be, in one example, integrally molded into the plastic ducts of the climate control system, thereby allowing ease in manufacturing with low cost.
Another advantage of the present invention is that it can reduce impingement or flow noise generated by flow turbulence contacting a discontinuity in the duct system. Thus, it can reduce turbulence upstream of a discontinuity or bend in ducts to reduce impingement or flow noise generated turbulent flow, generated from the fan, contacting the discontinuity in system.